1. Field of the Invention
This invention relates to wrenches, and more particularly, to open end reversible ratchet wrenches.
2. Description of the Prior Art
Open end reversible ratchet wrenches typically include a rotatable nut-engaging operating hub or jaw which has a slot extending from its periphery to a nut-engaging opening. In order to permit rotation in one direction and block rotation in the opposite direction, a ratchet is provided on the peripheral surface of the hub. The ratchet cooperates with ratchet pawls which engage the ratchet. However, as the hub rotates, the open slot is brought into registration with the position of engagement of a pawl rendering it ineffective. For this reason, it has become the practice in the prior art to use at least two pawls for each direction of rotation.
In U.S. Pat. No. 2,712,256 to H. L. Fish for example, two pairs of pawls are used, one pair for clockwise rotation and the other pair for counterclockwise rotation of the jaw. For every position of rotation of the jaw, at least one pawl of a selected pair of pawls is engaged with the ratchet to block rotation in a nonselected direction.
Although the open end wrench shown in U.S. Pat. No. 2,851,914 to W. F. Zeckzer has only two pawls, the two pawls are needed for each direction of rotation. The pawls each have two sets of triangular teeth and are swingable to engage one set of teeth with complementary ratchet teeth. Because of this tooth design, each pawl must also engage an abutment to block rotation of the operating jaw in a nonselected direction. The pawls are controlled by a control disc at the far end of the tool handle to select either clockwise, counterclockwise, or free rotation of the jaw. A spring biased pin engages locating recesses on the control disc to lock the disc in one of its three control positions. Elongated flexible strips which are movable in guide channels couple the control disc to the pawls. The Zeckzer wrench is thus relatively complex.
The ratchet-actuated open end wrench shown in U.S. Pat. No. 2,521,419 to A. E. G. Sellers also employs two actuating members for each direction of rotation of the jaw. While the wrench of the Fish patent uses pawls having only a single tooth, hook or point for engaging the ratchet teeth, the wrench of the Sellers patent uses actuating members having five teeth with substantially the same pitch as the rectangular teeth of the ratchet. The teeth of the actuating members have a blocking side for blocking rotation toward the blocking side and a sloped side which permits the ratchet teeth to slip thereover for rotation in the direction of the sloped side. Sellers, however, requires the operation of two separate selection mechanisms to select the direction of rotation, making the tool inconvenient to use. Sellers also provides for rectilinear sliding movement of the actuating members at an angle to the axis of the tool in chambers extending outwardly from the rotating jaw members, increasing the bulk of the tool.
The use of a single dog for each direction of rotation is shown in U.S. Pat. No. 2,353,901 to L. J. Jires. Each dog has a pair of spaced teeth, at least one of which engages the ratchet for all positions of the jaw. One dog blocks rotation of the jaw in the clockwise direction, and the other dog blocks rotation in the counterclockwise direction. However, Jires requires three rows of saw-tooth shaped ratchet teeth, and the pivot for the dogs is not fixed. The overall width of the wrench is relatively large when compared with the width of the nut opening or the width of the jaw. Separate control lugs are provided for operating the dogs.
British application No. 2,197,609A of A. Manwaring teaches in FIG. 8 the use of a single pivoted pawl for engaging an open ratchet for both directions of rotation. Triangular ratchet teeth are used. FIG. 7 of this reference shows a single rectilinearly slidable pawl for rotation in only one direction. In both cases, the pawl is operable for all positions of the jaw. A similar one-way wrench is shown in British patent application No. 2,197,234A of T. V. Jackson.